Equalizers can be used to compensate for signal loss resulting from transmission through a non-ideal medium. Such equalizers generally compensate for signal loss by applying a transfer function to the received signal with gain and frequency characteristics inverse to the degradation introduced by the transmission medium.
The transfer function 1+αG(s) is usually used to implement the inverse response of the cable or other transmission medium in adaptive equalizers designed to work with variable degrees of transmission degradation, such as those introduced by variable lengths of cable. The constant term 1 represents the absence of cable attenuation at direct current (frequency=0), and the transfer function G(s) is a high frequency boosting gain. The factor α is the adaptation factor and varies from 0, corresponding to 0 meters of cable, to 1, corresponding to the maximum cable length for which the equalizer is designed.
Example implementations and operational descriptions of sequential single- and multi-rate adaptive equalizers are disclosed in U.S. patent application Pub. No. 2003/0043897 A1, which is owned by the Assignee of the present application, and which is hereby incorporated into the present application by reference.